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Biomedical subjects

G Torelli

Publications and source records attributed to G Torelli.

At least 73 records · Page 4Linked to original sources
PubMed1997

L-arginine infusion decreases platelet aggregation through an intraplatelet nitric oxide release.

Nitric Oxide (NO) inhibits platelet aggregation via activation of an intraplatelet soluble guanylate cyclase which induces an increase in cyclic GMP (1). It has been also demonstrated that platelets contain a constitutive, calcium-dependent, NO synthase which is activated by collagen-induced platelet aggregation. This leads to a NO synthesis from L-Arginine (L-Arg), which in turn increases cyclic GMP and down-regulates platelet aggregation (2). In vitro administration of supraphysiological concentrations of L-Arg enhances platelet cyclic GMP levels by increasing NO production and reduces platelet aggregation. This effect is reversed by pre-incubation with NO-synthase inhibitors (3). These results indicate that the L-Arg: NO pathway plays an important role in the modulation of human platelet aggregation (4). In vivo L-Arg, when administered i.v., induces hypotension (5) and vasodilatation (6,7) in humans, and when orally supplemented reduces platelet aggregability both in hypercholesterolemic rabbits and healthy men (8,9).

Adenosine Diphosphate↗
PubMed1997

Human herpesvirus 6 (HHV-6) ORF-1 transactivating gene exhibits malignant transforming activity and its protein binds to p53.

The 357 amino acid open reading frame 1 (ORF-1), also designated DR7, within the SalI-L fragment of human herpesvirus 6 (HHV-6) exhibited transactivation of the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) promoter and increased HIV-1 replication (Kashanchi et al., Virology, 201, 95-106, 1994). In the current study, the SalI-L transforming region was localized to the SalI-L-SH subfragment. Several ORFs identified in SalI-L-SH by sequence analysis were cloned into a selectable mammalian expression vector, pBK-CMV. Only pBK/ORF1 transformed NIH3T3 cells. Furthermore, cells expressing ORF-1 protein produced fibrosarcomas when injected into nude mice, whereas control cells, expressing either no ORF-1 protein or C-terminal truncated (after residue 172) ORF-1 protein, were not tumorigenic. Western blot analysis of proteins extracted from the tumors revealed ORF-1 protein. Additional studies indicated that ORF-1 was expressed in HHV-6-infected human T-cells by 18 h. Co-immunoprecipitation experiments showed that ORF-1 protein bound to tumor suppressor protein p53, and the ORF-1 binding domain on p53 was located between residues 28 and 187 of p53, overlapping with the specific DNA binding domain. Functional studies showed that p53-activated transcription was inhibited in ORF-1, but not in truncated ORF-1, expressing cells. Importantly, the truncated ORF-1 mutant also failed to cause transformation. Analysis of several human tumors by PCR revealed ORF-1 DNA sequences in some angioimmunoblastic lymphadenopathies, Hodgkin's and non-Hodgkin's lymphomas and glioblastomas. The detection of ORF-1 sequences in human tumors, while not proof per se, is a prerequisite for establishing its role in tumor development. Taken together, the results demonstrate that ORF-1 is an HHV-6 oncogene that binds to and affects p53. The identification of both transforming and transactivating activities within ORF-1 is a characteristic of other viral oncogenes and is the first reported for HHV-6.

3T3 Cells↗
PubMed1997

Hepatitis C virus-induced leuko-thrombocytopenia and haemolysis.

Hepatitis C virus (HCV) has been recognized as the cause of thrombocytopenia occurring in patients with chronic hepatitis C, possibly through autoimmune mechanisms. A patient is described with B cell chronic lymphocytic leukaemia, presenting with a marked leuko-thrombocytopenia and an associated mild haemolysis secondary to HCV infection, in the absence of clinical and biochemical signs of hepatitis. Anti-HCV antibodies were detected in the serum both by ELISA and RIBA but not 2 months before the onset of cytopenia. The presence of HCV RNA was documented both in the peripheral blood mononuclear cells and in the bone marrow by reverse transcriptase polymerase chain reaction of the 5' untranslated region of the viral genome. Of interest, HCV RNA was also found in the serum, showing that viraemia was associated with the presence of circulating anti-HCV antibodies. HCV genotyping, performed by PCR amplification of the core region, revealed the presence of an unclassifiable genotype. The hypothetical mechanisms leading to HCV-induced cytopenia in this patient are briefly discussed. Treatment with corticosteroids was effective in controlling blood cell counts, without increasing viraemia and deterioration of liver disease. HCV infection should be considered in the differential diagnosis of possible causes of cytopenia, mainly in immunosuppressed patients, even in absence of clinical and biochemical signs of hepatitis.

Aged↗
PubMed1997

Detection of human herpes virus type 8 DNA sequences as a valuable aid in the differential diagnosis of Kaposi's sarcoma.

The occurrence of human herpes virus type 8 (HHV-8) DNA sequences was evaluated by polymerase chain reaction in 36 cases of cutaneous Kaposi's sarcoma (KS) (classic and associated with the acquired immunodeficiency syndrome) and in 88 pathologic entities that can histologically mimic KS, such as reactive and neoplastic vascular processes and lesions featuring focal or extensive spindle cell pattern. A positive reaction was detected in 16 (70%) of 23 samples of classic KS and 10 (77%) of 13 KS cases related to the acquired immunodeficiency syndrome. In particular, 4 (50%) of 8 samples in the patch stage were found to be positive, whereas in the plaque and nodular stages, HHV-8 DNA sequences were observed in 8 (67%) of 12 and 14 (87%) of 16 cases, respectively. KS cases that had yielded previous negative results were found to be positive for HHV-8 on nested polymerase chain reaction, except two cases of classic KS in the patch stage (6% of the total number of KS, 25% of cases in the patch stage). Reactive and neoplastic vascular processes and cutaneous lesions with a spindle cell component were consistently negative. HHV-8 detection by polymerase chain reaction can represent a valuable method for diagnosing KS, particularly in small skin biopsy samples that might show histologic overlap with non-KS lesions. In early patch stage lesions, however, the diagnostic value of the method is hampered by the occurrence of cases in which HHV-8 sequences are still undetectable.

DNA, Viral↗
PubMed1997

Human herpesvirus-6 reactivation in a longitudinal study of two HIV-1 infected patients.

After primary infection, human herpesvirus-6 (HHV-6) persists in latent form and can be reactivated in immunocompromised subjects. A longitudinal study of HHV-6 infection was carried out in two HIV-1 seropositive patients to provide in vivo evidence of HHV-6 reactivation. Concomitant with a significant rise of anti-HHV-6 IgG detected by IFA, a transient increase of HHV-6 viral load was shown in PBLs by PCR. During HHV-6 reactivation it was also identified either cell-free HHV-6 by PCR in plasma or IgM antibody titers. HHV-6 reactivation was followed by a temporary decrease in CD4+ count and by a progressive dramatic loss of CD4+ during the following 18 months. HHV-6 strain characterization by PCR demonstrated that first patient (MM) initially showed the B variant, followed by reactivation and persistence of the A variant, while in the second (SG) only the A variant was detected. The evidence of HHV-6 reactivation suggests its involvement in immunologic damage underlying the disease.

AIDS-Related Opportunistic Infections↗
PubMed1996

Frequency and distribution of herpesvirus-like DNA sequences (KSHV) in different stages of classic Kaposi's sarcoma and in normal tissues from an Italian population.

The frequency and distribution of herpesvirus-like DNA sequences (KSHV) were investigated by PCR in the pathologic skin lesions of a series of 22 HIV-negative elderly patients with classic Kaposi's sarcoma (KS) from Italy, one of the few regions of the world where classic KS is prevalent. Viral sequences were clearly identifiable in 15 cases, in particular in 2 of 5 patch, in 3 of 6 plaque and in 10 of 11 nodular lesions. Our findings confirm the association of these herpesvirus-like DNA sequences with KS in unrelated populations, providing evidence of the putative KS-associated agent in all different histologic lesions of the disease, mainly in the nodular stage. The search for other herpesviruses by PCR showed that Epstein-Barr virus (EBV) sequences were present in 7 of 22 pathologic skin lesions. In 4 cases, both EBV and KSHV were present. On the contrary, all 22 classic KS specimens were negative for human herpesvirus-6 sequences. Two of 3 patch and the 1 nodular lesions from AIDS-related KS patients examined were positive for KSHV but negative for both EBV and HHV-6 sequences. Furthermore, we evaluated the prevalence of KSHV sequences in the normal population of the same geographical area. Thirteen peripheral blood mononuclear cell samples, 9 salivary gland tissues and 6 saliva samples from healthy subjects were invariably found negative for KSHV, using the same PCR technique. Of interest, 2 of 11 hyperplastic tonsils harboured these herpesvirus-like sequences, suggesting that, like other herpesviruses, the KS- associated agent may be harboured in a proportion of normal individuals and tonsils may represent at least one of the possible reservoirs of this putative lymphotropic gamma-herpesvirus in vivo.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Human herpesvirus-8 DNA sequences in human immunodeficiency virus-negative angioimmunoblastic lymphadenopathy and benign lymphadenopathy with giant germinal center hyperplasia and increased vascularity.

Human herpesvirus-8 (HHV-8) DNA sequences have been reported to be strictly associated not only with various forms of Kaposi's sarcoma but also with an unusual subgroup of acquired immunodeficiency syndrome (AIDS)-related B-cell lymphomas. A possible relation of this putative virus also with multicentric Castleman's disease (MCD) has been recently suggested. We used polymerase chain reaction to look for the presence of HHV-8 sequences in a well characterized series of benign, atypical, and malignant lymphoid tissues from 45 Hodgkin's disease and 43 non-Hodgkin's lymphoma (NHL) cases, as well as from 5 MCD, 15 angioimmunoblastic lymphadenopathy (AILD), and 23 benign lymphadenopathy cases. Among the 38 AIDS-related lymphoid lesions, only 1 NHL and 1 persistent generalized lymphadenopathy (PGL) case were positive. Furthermore, among the 92 non-AIDS-related lymphoproliferative disorders, HHV-8 sequences were detected in 3 classic AILD cases and in 4 reactive lymphadenopathies. Six of 9 HHV-8 positive lymphoid lesions (1 NHL, 1 PGL, 1 AILD, and 3 reactive lymphadenopathy cases) were also positive for Epstein-Barr viral sequences. The four human immunodeficiency virus (HIV) negative lymphadenopathies positive for HHV-8 sequences showed an almost identical histology, characterized by a predominantly follicular lesion, with giant germinal center hyperplasia, and increased vascularity, resembling HIV-related lymphadenopathy and MCD. Our results, while providing the first evidence of the presence of HHV-8 sequences in AILD cases, suggest a possible association of these herpes viral sequences with a distinct histologic type of non-neoplastic lymphadenopathy, not associated with other common herpes infections.

Base Sequence↗
PubMed1996

An encephalitic episode in a multiple sclerosis patient with human herpesvirus 6 latent infection.

All the human herpesviruses may cause central nervous system (CNS) diseases, including benign aseptic meningitis or fatal encephalitis. It has recently been stated that human herpesvirus 6 (HHV-6) may also be neuropathogenic in children after primary infection, while in the adult, cases of fatal encephalitis have been reported only in immune-compromised hosts such as AIDS patients, and in one case of an immunosuppressed bone marrow transplant patient. We describe a multiple sclerosis (MS) patient, carrier of HHV-6 latent infection, who experienced an acute inflammation of the CNS diagnosed as encephalitis. HHV-6 specific genomic sequences have been detected by PCR in the patient's PBMCs DNA collected before and during the encephalitis. The PCR performed in the CSF in course of the acute episode was positive, while the CSF collected before the encephalitis was negative. This finding is consistent with an acute encephalopathy caused by the reactivation of a HHV-6 latent infection within the CNS, in a patient with altered immune response due to MS.

Adult↗
PubMed1996

Additional neoplasms and HCV infection in low-grade lymphoma of MALT type.

Several chronic inflammatory conditions and genetic alterations are likely to be involved in the pathogenesis of low-grade lymphoma of MALT type. In a well-characterized series of 27 patients with low-grade lymphoma of MALT type, we studied: (1) the incidence of other neoplasms, which might be indicative of genetic instability, apparently a characteristic of this disease; (2) the prevalence of serologic and molecular markers of HCV infection, which has been found in association with other lymphoproliferative disorders. Three patients had one or more additional cancers; a total of eight tumours, five of which occurred in the same patient, suggests the presence of some genetic instability in at least some cases of the disease. Rather unexpectedly, anti-HCV antibodies and HCV RNA sequences were documented in 50% of the patients examined, without elevation of serum transaminases. Of interest, the two patients with parotid and conjunctival MALT lymphomas, respectively, with a previous history of Sjögren's syndrome, were HCV positive. We suggest, for the first time, that HCV may be considered, in addition to Helicobacter pylori, as another potential infectious co-factor in the multistep pathogenesis of low-grade lymphomas of MALT type.

Adult↗
PubMed1996

Sensitive detection of circulating breast cancer cells by reverse-transcriptase polymerase chain reaction of maspin gene.

BACKGROUND: Maspin, a recently identified protein related to the family of serpins, is believed to play a role in human breast cancer. In an effort to improve the present methods of detection, we have developed a reverse-transcriptase polymerase chain reaction (RT-PCR) assay for maspin transcript to identify small numbers of mammary carcinoma cells in the peripheral blood and bone marrow of patients with breast cancer. PATIENTS AND METHODS: Five non-neoplastic mammary tissue samples, 13 breast cancer specimens as well as 17 peripheral blood and 4 bone marrow samples from normal subjects were screened for the presence of maspin mRNA by RT-PCR. The same assay was applied to peripheral blood or bone marrow samples obtained from 29 patients with stages I to IV breast cancer. RESULTS: By RT-PCR it was possible to amplify maspin mRNA in all of the primary and metastatic breast cancer specimens, but in none of the normal hemopoietic samples from healthy donors. Thus, detection of maspin transcript in the peripheral blood or marrow of a patient known to have breast cancer is indicative of the presence of mammary carcinoma cells. In reconstitution experiments, maspin RT-PCR reliably detected 10 mammary carcinoma cells in 1 million normal peripheral-blood mononuclear cells (PBMCs). None of the 9 patients with stages I, II, or III breast cancer had maspin transcript in peripheral blood. Of note, 3 of 9 patients with stage IV breast cancer receiving systemic therapy at the time of sample collection, but only 1 of 11 patients with stage IV not receiving therapy, had detectable maspin transcript in peripheral blood. Moreover, 3 marrow specimens from stage IV patients tested positive by this assay. CONCLUSIONS: This pilot study suggests that maspin RT-PCR assay is a sensitive, specific and sufficiently rapid method for detection of small numbers of circulating cells and marrow micrometastases in breast cancer patients. The possibility of applying this assay in the detection of tumor cell contamination of both marrow and stem-cell apheresis harvests of breast cancer patients merits further investigation.

Breast Neoplasms↗
PubMed1996

Lymphotropic herpes virus (EBV, HHV-6, HHV-8) DNA sequences in HIV negative Castleman's disease.

Aim-To evaluate the possible involvement of lymphotropic herpes viruses in Castleman's disease.Methods-Archival formalin fixed, paraffin wax embedded biopsy specimens from 16 HIV negative patients (11 with localised and five of multicentric disease) were studied. Epstein-Barr virus (EBV), human herpes virus-6 (HHV-6) and human herpes virus-8 (HHV-8) DNA was detected using PCR. PCR was also used to characterise the EBV genomes and the clonal status of the lesions.Results-EBV sequences were identified in nine (56%) cases. The main EBV genotype detected was type 1. Two (12%) cases were positive for both HHV-6 and EBV sequences. HHV-8 sequences were detected in one case of localised Castleman's disease, the sequence of which differed from that of the HHV-8 prototype. No clonal immunoglobulin gene rearrangements were found.Conclusions-EBV DNA was detected in a substantial proportion of cases, suggesting that it may have a role in the pathogenesis of Castleman's disease, unlike HHV-6 which was detected rarely. This is the first report of HHV-8 specific sequences in the localised from of the disease.

Journal Article↗